Color Characteristics of Irradiated Vacuum-Packaged Pork, Beef, and Turkey

Changes in color of irradiated meat were observed to be species-dependent. Irradiated pork and turkey became redder due to irradiation but irradiated beef a* values decreased and yellowness increased with dose and storage time. The extent of color change was irradiation dose-dependent and was not related to myoglobin concentration. Visual evaluation indicated pork and turkey increased in red ness whereas beef decreased in redness as dose levels increased. Reflectance spectra showed that irradiation induced an oxymyoglobin-like pigment in pork and that both oxymyoglobin and metmyoglobin developed in beef as a result of irradiation.     

Color, Oxidation-Reduction Potential, and Gas Production of Irradiated Meats from Different Animal Species

ABSTRACT: Turkey breasts, pork loins, and beef loins were aerobically or vacuum-packaged and electron beamirradiated at 3 kGy. Irradiation increased the redness of turkey breast regardless of packaging or storage. Irradiation drastically decreased the redness of aerobically packaged beef loin. Irradiated meats produced higher amounts of CO and CH₄ than nonirradiated. The oxidation-reduction potential (ORP) of meats decreased after irradiation, but increased during the storage. Little differences in CO and ORP values among the irradiated meats from different species were detected. This indicated that CO and ORP were not the only factors involved in the color changes of beef loin by irradiation.     

Cholesterol oxidation products in irradiated raw meat with different packaging and storage time

The effect of irradiation and packaging conditions on the formation of cholesterol oxidation products (COPs) as well as lipid oxidation products was determined in raw turkey leg, beef, and pork loin meat during 7 days of storage. Ground turkey leg, beef, and pork loin muscles were prepared as patties. The patties were individually packaged either in oxygen-permeable or impermeable bags, irradiated at 0 or 4.5 kGy using a Linear Accelerator, and stored at 4°C. The COPs such as 7-hydroxycholesterol, 7β-hydroxycholesterol, and 7-ketocholesterol were detected in fresh raw meats at 0 day at the level of 10.9 to 49.2 μg/g lipid. After 7 days of storage, other COPs such as epoxides, 20-hyroxycholesterol, and choletanetriol were formed in mainly aerobically packaged and irradiated raw meats. Packaging effect was more crucial on the cholesterol and lipid oxidation than irradiation. In aerobically packaged and irradiated meats, turkey leg muscles had higher COPs value than beef or pork did. COPs and thiobarbituric acid reactive substances (TBARS) values had a strongly positive correlation in turkey leg and pork. But, cholesterol oxidation in beef proceeded in irradiated and aerobically stored samples despite of its low level of TBARS value.     

Effect of irradiation and packaging conditions after cooking on the formation of cholesterol and lipid oxidation products in meats during storage

The effect of irradiation and packaging conditions on the content of cholesterol oxidation products (COPs) and lipid oxidation in cooked turkey, beef, and pork during storage was studied. Ground turkey leg, beef, and pork were cooked, packaged either in oxygen-permeable or oxygen-impermeable bags, and irradiated at 0 or 4.5 kGy. Lipid oxidation and COPs were determined after 0 and 7 days of storage at 4°C. Packaging of cooked meat was more important than irradiation in developing COPs and lipid oxidation in cooked meats during storage. 7-Hydroxycholesterol, 7β-hydroxycholesterol, β-epoxide, and 7-ketocholesterol were among the major COPs formed in cooked turkey, beef, and pork after storage, and their amounts increased dramatically during the 7-day storage in aerobic conditions. Irradiation had no significant effect on the amounts of any of the COPs found in cooked turkey and beef, but increased (P<0.05) the amounts of - plus 7β-hydroxycholesterol, β-epoxide, 7-ketocholesterol, and total COPs in aerobically packaged cooked pork. The amounts of COPs and lipid oxidation products (TBARS) closely related to the proportion of polyunsaturated fatty acids in meat. The results indicated that the composition of fats in meat is important on the oxidation rates of lipids and cholesterol, and packaging is far more important than irradiation in the formation of COPs and lipid oxidation in cooked meat.     

Prevention of Pinking, Off-odor, and Lipid Oxidation in Irradiated Pork Loin Using Double Packaging

ABSTRACT: Lipid oxidation, color, volatiles, and sensory evaluation of double-packaged pork loin were determined to establish a modified packaging method that can improve the quality of irradiated pork loins. Vacuum-packaged irradiated samples produced dimethyl sulfide and dimethyl disulfide responsible for irradiation off-odor, whereas lipid oxidation was promoted under aerobic conditions. Exposing double-packaged irradiated pork to aerobic conditions for 1 to 3 d was effective in controlling both lipid oxidation and irradiation off-odor, regardless of packaging sequence. Sensory panels could distinguish the decrease in irradiation off-odor intensities by modifying the packaging method. However, carbon monoxide heme pigments, responsible for the increased redness by irradiation, were not effectively controlled by double packaging alone.     

Effect of vitamin E, low dose irradiation, and display time on the quality of pork

A 4×2×3 factorial experiment was designed to investigate the effect of supplemental vitamin E (0, 100, 200, and 300 mg/kg feed), irradiation and days in display on quality characteristics of aerobically packaged ground pork and vacuum packaged loin chops. Color, thiobarbituric acid reactive substances (TBARS), olfactory and sensory characteristics were evaluated. Samples held in display for 3 d were used for sensory evaluation. In the ground pork, irradiation (1.9 kGy) increased "wetdog" flavor, increased a(*) (redness) and decreased L(*) (lightness) and b(*) (yellowness) values but had no effect on TBARS. However, as display time (0, 4, and 8 days) increased; the differences in a(*) values diminished and putrefying and fishy odors were higher in non-irradiated samples than irradiated. Supplemented vitamin E had no effect on TBARS, odor, and color measures; but increased the juiciness of ground pork regardless of irradiation. Similarly, in the loin chops, irradiation (1.5 kGy) increased a(*) value and "wetdog" flavor; but decreased b(*) value regardless of vitamin E supplementation. Also, irradiation reduced putrefying, and fishy odors during longer display times. TBARS increased with increased display time but was not affected by vitamin E supplementation. These results indicate that in aerobically packaged ground pork and vacuum packaged loin chops, radiolytic odors and color changes cannot be mediated with vitamin E supplementation. Display time and irradiation are significant in determining color and odor changes.     

Volatile profiles, lipid oxidation and sensory characteristics of irradiated meat from different animal species

Irradiated meats produced more volatiles and higher 2-thiobarbituric acid reactive substances (TBARS) than nonirradiated regardless of animal species. Irradiation not only produced many new volatiles not found in nonirradiated meats but also increased the amounts of some volatiles found in nonirradiated meats. The amounts of volatiles in aerobically packaged irradiated meats decreased with storage while those of nonirradiated meats increased. TBARS values were the highest in beef loin, followed by turkey breast and pork loin regardless of irradiation, packaging, and storage time. TBARS of meats showed positive correlation with total volatiles, but preference scores between irradiated and nonirradiated were similar.     

Effect of low dose gamma radiation on lipids in five different meats

Five types of meats were irradiated by gamma radiation up to a dose of 10 kGy. The m. longissimus dorsi from pork, lamb and beef was irradiated as well as turkey leg and turkey breast muscle. After irradiation, the lipids were extracted from the muscles to ascertain the effect of irradiation. Peroxide and iodine values along with malonaldehyde concentration were used to assess any damage made to the lipids, and to note any significant differences in these compounds due to the type of muscle tissue. Peroxide and iodine values showed that at low irradiation dose, <10 kGy, there was no significant change in any of the meat lipids. Malonaldehyde concentration changed significantly at the micromolar level due to irradiation dose, but only in turkey breast muscle.     

Effects of Ascorbic Acid and Antioxidants on the Color of Irradiated Ground Beef

Irradiation significantly decreased the redness of ground beef (P < 0.05), and the visible color of beef changed from a bright red to a green/brown, depending on the age of meat. Addition of ascorbic acid (0.1%, wt/ wt) in ground beef prior to irradiation prevented color changes in irradiated beef, and the effect of ascorbic acid became greater as the age of meat or storage time after irradiation increased. Ground beef with added ascorbic acid had significantly lower oxidation‐reduction potential than the control (P < 0.05), and the low oxidation‐reduction potential of meat helped maintain the heme pigments in reduced form. Sesamol +α‐tocopherol had no effect in stabilizing color of irradiated beef.     

Citric acid and sodium citrate effects on pink color development of cooked ground turkey irradiated pre- and post-cooking

The effects of citric acid (0.15%, 0.3%) and sodium citrate (0.5%, 1.0%) on pink color development in ground turkey following irradiation (0, 2.5, 5.0kGy) were examined. Citric acid and sodium citrate had little effect on pink color when samples were irradiated prior to cooking. In contrast, when samples were cooked prior to irradiation, citric acid (0.3%) and sodium citrate (1.0%) reduced redness as indicated by eliminating a reflectance minimum at approximately 571nm, lessening greater reflectance in the red wavelength region, and preventing greater reducing conditions caused by irradiation. Citric acid significantly reduced pH and yields whereas sodium citrate reduced pH and yields to a lesser extent. Both citric acid and sodium citrate are potential ingredients that can be added during processing to prevent undesirable pink color in precooked irradiated ground turkey and therefore can result in greater acceptance of irradiated products by consumers.     

Mechanisms of Pink Color Formation in Irradiated Precooked Turkey Breast Meat

ABSTRACT: Precooked turkey breast meat was aerobically packaged or vacuum-packaged and irradiated at 0, 2.5, or 5.0 kGy. CIE color, reflectance, oxidation-reduction potential (ORP), gas production, and lipid oxidation were determined at 0, 7, and 14 d. Irradiation increased redness of vacuum-packaged meat, and the redness was distinct and stable under vacuum. Irradiation decreased ORP and produced carbon monoxide (CO). This indicated that the pink color was caused by the heme pigment-CO complex formation. The reflectance of meat and the absorption spectra of myoglobin solution supported the assumption that denatured CO-myoglobin is the pigment in irradiated precooked turkey breast.     

Effects of Ascorbic Acid and Antioxidants on the Lipid Oxidation and Volatiles of Irradiated Ground Beef

Beef loins, aged for different lengths of time post slaughter, were treated with ionizing radiation. Irradiated ground beef produced volatile sulfur compounds (S‐volatiles) responsible for the unique irradiation odor and accelerated lipid oxidation. The quality changes by irradiation became greater as aging and storage time increased. During aerobic storage, the S‐volatiles disappeared whereas volatile aldehydes drastically increased in irradiated beef. Addition of ascorbic acid at 0.1% (wt/wt) or sesamol +α‐tocopherol at each 0.01% level to ground beef before irradiation effectively reduced lipid oxidation and S‐volatiles. As storage time increased, however, the antioxidant effect of sesamol + tocopherol in irradiated ground beef was superior to that of ascorbic acid.     

Gamma Irradiation Effects on Thiamin and Riboflavin in Beef, Lamb, Pork, and Turkey

A study was made of the loss of thiamin and riboflavin due to gamma irradiation of beef, lamb and pork longissimus dorsi, turkey breast and leg muscles. Thiamin losses averaged 11%/kiloGray (kGy) and riboflavin losses 2.5%kGy above three kGy. The rate of loss of thiamin in beef was higher than that in lamb, pork and turkey leg, but not turkey breast. with losses of 16%/kGy in beef and 8%/kGy in lamb. The rate of thiamin loss was not related to sulfhydryl, protein, moisture, fat or water content, pH or reducing capacity by redox titration. Loss of riboflavin was not different among species. Any detriment from such slight losses would seem to be more than compensated by the advantage of controlling bacteriological contamination by irradiation processing.     

Lipid Oxidation and Color Stability in Restructured Meat Systems during Frozen Storage

Salt and combinations of salt with phosphates and antioxidants were investigated for their role in lipid oxidation and discoloration in restructured beef, pork, and turkey steaks during storage at - 10°C for 16 wk, 8 wk and 8 wk, respectively. Lipid oxidation and discoloration occurred simultaneously in pork and turkey, but beef color loss occurred much earlier than did lipid oxidation. Phosphates were effective in inhibiting lipid oxidation in beef (4 wk), pork (8 wk) and turkey (6 wk). Tertiary butylhydroquinone inhibited lipid oxidation in pork and turkey steaks, but, overall, neither prevented discoloration. Results indicate discoloration and lipid oxidation are interrelated, and pigment oxidation may catalyze lipid oxidation.     

Effects of aging time and natural antioxidants on the color, lipid oxidation and volatiles of irradiated ground beef

Beef rounds aged for one, two, or three weeks after slaughtering were ground added with 0.05% ascorbic acid+0.01% α-tocopherol or 0.05% ascorbic acid+0.01% α-tocopherol+0.01% sesamol, placed on Styrofoam trays and wrapped with oxygen-permeable plastic film, and treated with electron beam irradiation at 0 or 2.5kGy. The meat samples were displayed under fluorescent light for 7d at 4°C. Color, lipid oxidation, volatile analysis, oxidation-reduction potential (ORP) and carbon monoxide (CO) production were determined at 0, 3, and 7d of storage. Irradiation increased lipid oxidation of ground beef regardless of their aging time and storage period. As aging time increased lipid oxidation increased. Adding sesamol increased the effectiveness of ascorbate and tocopherol combination in reducing lipid oxidation especially as aging and storage time increased. The redness of beef were decreased by irradiation and adding ascorbic acid and α-tocopherol before irradiation was effective in maintaining the redness of irradiated ground beef over the storage period. The combination of ascorbic acid+α-tocopherol to ground beef was more effective in reducing ORP than adding sesamol. Irradiation increased CO production from all ground beef regardless of aging time or additives treatments. Volatile sulfur compounds produced by irradiation at Day 0 disappeared over the storage period. Alcohol greatly increased in all nonirradiated beef, but volatiles aldehydes only in irradiated control beef. Antioxidant treatments were effective in reducing aldehydes in ground beef during storage.     

Fat Content Influences the Color, Lipid Oxidation, and Volatiles of Irradiated Ground Beef

ABSTRACT:  Ground beef with 10%, 15%, or 20% fat were added with none, 0.05% ascorbic acid + 0.01%α-tocopherol, or 0.05% ascorbic acid + 0.01%α-tocopherol + 0.01% sesamol, and irradiated at 0 or 2.5 kGy. The meat samples were displayed under fluorescent light for 14 d at 4 °C. Color, lipid oxidation, volatiles, oxidation-reduction potential (ORP), and carbon monoxide (CO) production were determined during storage. Irradiation increased lipid oxidation and total volatiles of ground beef regardless of fat contents. Ascorbic acid +α-tocopherol + sesamol treatment was the most effective in reducing lipid oxidation during storage. The production of ethanol in nonirradiated ground beef increased dramatically after 7 d of storage due to microbial growth. Total aldehydes and hexanal increased drastically in irradiated control over the storage period, but hexanal increased the most by irradiation.  L *-values was decreased by irradiation, but increased in all meat regardless of fat contents as storage period increased. Irradiation reduced the redness, but fat contents had no effect on the  a *-value of ground beef. Sesamol lowered, but ascorbic acid +α-tocopherol maintained the redness of irradiated beef up to 2 wk of storage. The yellowness of meat was significantly decreased by irradiation. The reducing power of ascorbic acid +α-tocopherol lasted for 3 d, after which ORP values increased. Irradiation increased CO production regardless of fat content in ground beef. In conclusion, up to 20% fat had no effect on the quality change of irradiated ground beef if ascorbic acid +α-tocopherol was added.     

The effect of ionising radiation on the colour of beef, pork and lamb

The effect of irradiation (0 and 5 kGy) of beef, pork and lamb portions in retail overwrap packs and subsequent storage at 4°C was studied in relation to colour changes. The colour of the exterior surface of beef and pork was measured on the same samples on each day of storage for up to 7 days post irradiation. On day 7 the colour of a freshly cut surface was measured. The colour of both the exterior and a freshly cut surface of lamb, in similar retail overwrap packs was measured at 2, 5 and 7 days, post irradiation, different samples being used on each day of measurement. L* values of irradiated beef increased significantly with storage and a* values for unirradiated samples decreased significantly with storage. For lamb there was a general increase in L* and h(o) values and a decrease in a*, b* and C* values with storage. Analyses of the day 7 data showed statistically significant effects for species on all CIELAB parameters. Irradiation resulted in significantly higher hue angle (h(o)) values and the a*, b* and C* values were significantly higher on the exterior than freshly cut surface. There were a number of statistically significant 2 factor and 3 factor interactions. The role of formation of a carboxyhaem pigment in the colour of irradiated meat is discussed. The problem of interpretation of pigment changes from CIELAB values is highlighted.     

Acceptance and Species Identification of Turkey Steaks Prepared with Beef, Pork, Lamb, and Turkey Fat

Fabricated extruded steaks were prepared from turkey meat, salt, phosphate, and water plus 15% beef, pork, lamb, or turkey fat. The grilled samples recieved relatively high hedonic scores from a sensory panel. The flavor, juiciness, and overall quality of the samples made with pork, beef, and turkey fat were preferred significantly over the samples made with lamb fat. Panel members tended to consider all samples as being pork flavored. Beef, pork, or turkey fat could be used as the fat in a fabricated, extruded steak without affecting the relative acceptability of the cooked product.     

Effect of electron-beam irradiation before and after cooking on the chemical properties of beef, pork, and chicken

Ground beef, pork, and chicken thigh meats were irradiated at 0 or 5.0kGy before and after cooking and then stored at -40°C in oxygen permeable bags. The pH, lipid oxidation, volatiles, and carbon monoxide production of the meat were determined at 0 and 6months of storage. The pH values of raw meats from different animal species were different (5.36-6.25) and were significantly increased by cooking, irradiation, and storage (p<0.05). Irradiation had no effect on the TBARS values of ground beef and pork, but significantly increased the TBARS of chicken thigh meat. Cooking, whether it was done before or after irradiation, caused significant increase in TBARS and was most significant in chicken and pork. The numbers of volatiles analyzed by GC/MS were higher in irradiated meats than the non-irradiated ones regardless of meat source. Sulfur-containing compounds were newly produced or increased by irradiation, but dimethyl disulfide and dimethyl trisulfide were not detected in the non-irradiated meats regardless of cooking treatment. Irradiation time, whether done before or after cooking, had little effect on the TBARS, volatiles, and carbon monoxide production in the meat.     

Effect of ionizing radiation on quality characteristics of vacuum-packaged normal,pale–soft–exudative,and dark–firm–dry pork

Normal, pale–soft–exudative (PSE), and dark–firm–dry (DFD) pork Longissimus dorsi muscles were vacuum-packaged, irradiated at 0, 2.5 or 4.5 kGy, and stored at 4 °C for 10 days. The pH, color and lipid oxidation of pork were determined at 0, 5 and 10 days of storage. Volatile production from pork loins was determined at Day 0 and Day 10, and sensory characteristics at Day 7 of storage. Irradiation increased the redness of vacuum-packaged normal, PSE and DFD pork. However, the 2-thiobarbituric acid reactive substances (TBARS) values of three types of pork were not influenced by irradiation and storage time. Irradiation increased the production of sulfur (S)-containing volatile compounds, such as mercaptomethane, dimethyl sulfide, carbon disulfide, methyl thioacetate, and dimethyl disulfide, as well as total volatiles in all three types of pork. Normal pork produced higher levels of total and S-containing volatile compounds than the PSE and DFD pork did. The volatiles produced by irradiation were retained in the vacuum packaging bag during storage. Although the odor preference for the three meat types of pork was not different, the panelists could distinguish irradiated meat from the non-irradiated. Industrial relevance: Several US meat companies have already started test-marketing irradiated meat products. Irradiation and the subsequent storage of pork improved the color of PSE and DFD pork, and showed generally similar effects on the production of volatiles, except that there appeared to be a lower level of S-volatiles in the PSE than in the other two samples. This indicated that irradiation can increase the utilization of low-quality pork (PSE and DFD). DFD pork, in particular, which has shorter shelf-life than the others, could benefit the most from irradiation because the shelf-life of DFD meat can be extended significantly by both the methods of vacuum packaging and irradiation.